Sterilized footwear

ABSTRACT

FOOTWEAR SUCH AS A SHOE HAS A WOODEN SOLE TO WHICH IS SECURED AN UPPER MADE OF A FABRIC COATED WITH EMULSIFIED POLYVINYLCHLORIDE CONTAINING A SOFTENING AGENT AND A STABILIZING AGENT. SUCH FOOTWEAR IS CAPABLE OF BEING REPEATEDLY STERILIZED FOR A PERIOD BETWEEN 15 AND 60 MINUTES AND AT A TEMPERATURE BETWEEN 100*C. AND 150* C. WITHOUT SUBSTANTIALLY CHANGING ITS SHAPE, AND IS HENCE PARTICULARLY SUITABLE FOR USE IN AN ENVIRONMENT REQUIRING THE USE OF STERILIZED FOOTWEAR.

United States Patent ice 3,552,038 STERILIZED FOOTWEAR Rune Edberg,Orebro, Sweden, assignor to Arbesko Aktiebolag, Orebro, Sweden N0Drawing. Filed Sept. 30, 1968, Ser. No. 763,956 Claims priority,application Switzerland, Dec. 11, 1967, 16,952/67 Int. Cl. A431; 00/00U.S. Cl. 362.5 6 Claims ABSTRACT OF THE DISCLOSURE At, for instance, themanufacture of pharmaceuticals, and in operating rooms in hospitals, itis of very great importance that both people and their garments, as wellas instruments, are sterilized. However, it has hitherto not beenpossible to sterilize the footwear used by personnel in operating roomsand the personnel in the sterile rooms in factories wherepharmaceuticals are made. This is an obvious disadvantage, and attemptshave been made to find sterilized footwear somewhere in the world.However, this has not led to any success. Extensive research has alsobeen carried on to develop sterilizable footwear. Regrettably, this hasnot led to any results.

In the above-mentioned dismal situation, it has become possible, throughthe present invention, to produce footwear that will withstand beingsterilized a number of times. Sterile footwear has thereby been obtainedwhich also has an economic life.

The sterilization to which the footwear is to be subjected is to takeplace at a temperature of between 100 and 150 C., particularly between128 and 130 C. The sterilization is to last for a time of between 15 and60 minutes, particularly, however, 30 minutes.

According to the invention, the sterilizable footwear is of theclog-bottom type, consisting of a bottom made of wood and an upper madeof flexible material, which is applied to the bottom in a conventionalway. By choosing a suitable combination of materials among knownmaterials, it has been possible to develop footwear that can besterilized. Making such a choice can be regarded as the result ofperseverance, of a non-patentable nature, but with consideration to whathas been stated above, the combination chosen must not be an obviousmeasure. The combination consists of choosing a kind of wood for thebottom that can be subjected to the above-mentioned sterilizationwithout becoming distorted. Nails, if any, in the bottom must notloosen. Moreover, the bottom is to be made of such material that itretains its shape and flexibility.

It has now proved that the kind of wood that meets the above-mentionedrequirements, according to the invention should be beech-wood, and thenparticularly common, ordinary beech-wood. It has also proved that theupper should consist of a plastic material which is availablecommercially and is sold under the trade name Gekalit. For fastening theupper to the bottom it is appropriate to use copper nails.

Gekalit consists of a woven fabric, particularly cotton fabric, to whichhas been applied a plastic, and then Patented Jan. 5, 1971 polyvinylchloride with a softener and a stabilizer. The plastic shouldappropriately be applied so that a coherent layer is formed. It hasproved to be advantageous to use a fabric with a weight of 200 grammesper square metre. The softener can consist of a phthalic acid ester. Abarium-cadmium compound is a suitable stabilizer.

Before its application to the fabric, the polyvinyl chloride has beenobtained through emulsion polymerization.

On the inside of the Gekalit, i.e. the upper, a moistureabsorbing layercan be applied through gluing. Also this layer consists of a fabric,which has been impregnated with an elastomer. The moisture-absorbinglayer also consists of a cotton fabric, which appropriately has a weightof 200 grammes per square metre. The elastomer consists of polyurethane.A suitable glue for fastening the two layers together is a polyurethaneglue.

The bottom according to the present invention can have exactly more orless the same form as the bottom of ordinary clogs. The bottom canmoreover be provided with a tread, which can either be a wear tread or afriction tread. This tread can be applied with glue or with nails. Thetread should then have the form of a sole, but the bottom can of coursealso be coated with a liquid layer that can stiffen. The requirement forthe tread is that it will withstand being sterilized. Further, it isappropriate to allow the bottom to have arrangements by means of whichstatic electricity in the bottom can be removed.

The upper should appropriately be nailed on to the bottom by means ofcopper nails. It is then the edge of the upper which is nailed to thebottom. It is then advisable to have a nylon band under the heads of allof the nails. Over the bottom the upper forms a band or a cavity underwhich the users foot can be inserted, so that the bottom can be securedto said foot.

It has proved that a shoe according to the present invention, i.e.consisting of beech-wood, although not red-beech, and said upper made ofGekalit, can be sterilized at least a hundred times. With considerationto the frequency of the sterilizations, such a sterilizable shoe willhave a life corresponding to that of a similar shoe which is notsubjected to sterilization.

What is claimed is:

1. Footwear capable of being repeatedly sterilized comprising:

a wooden sole; and

an upper secured to said sole, and made of a fabric coated withemulsified polyvinylchloride containing a softening agent and astabilizing agent whereby the coated fabric upper and the wooden solesubstantially retain shape when repeatedly subjected to sterilizingtreatments for a period of 15 to 60 minutes and at a temperature of C.to C.

2. The footwear according to claim 1 wherein said softening agent is aphthalic acid ester.

3. The footwear according to claim 1 wherein stabilizing agent is abarium-cadmium compound.

4. The footwear according to claim 1 wherein upper is secured to saidsole by copper nails.

5. The footwear according to claim 1 wherein sole consists of beechwood.

6. The footwear according to claim 1 wherein said fabric is a wovenfabric containing primarily cotton fibers.

said

said

said

References Cited UNITED STATES PATENTS 1,053,442 2/1913 Rouse 36332,221,132 11/1940 Girardi 3633 2,460,838 2/ 1949 Margolin 36-33 PATRICKD. LAWSON, Primary Examiner

